I have 2, When my brother was around 3 he was looking out the window at the fog with my older brothers mate (then 22ish) he said it's really foggy out to which my bro's mate said 'yea, like looking through cataracts' My little bro looked really confused for a minute and then said 'cats arses? how can you see through cats arses?'

The other one, again when my little bro was about 3, he was trying to get past his dad to go play and he stood patiently for 5 minutes then started humming 'in the jungle' and then started singing 'you're in my way' to the tune.